This Phase II SBIR contract will produce an engineering prototype of an integrated system for recording electroencephalographic signals from over 100 electrodes simultaneously. This prototype will facilitate reliable and rapid placement of electrodes and will feature automated impedance checking and calibration. This prototype will include a novel way of ascertaining the three dimensional locations of electrodes, which is essential to allow proper interpretation of data. The following technical objectives will be met: 1) construction of recording hat with electrolyte injection system, 2) design and implementation of automatic impedance measuring circuits, 3) use of digital photography for electrode position assessment, 4) modification of multichannel amplification and filtering systems, 5) fabrication of system controller board, 6) design and fabrication of digital signal processing and data-transfer adaptor boards, 7) testing of components and integrated system.